Design of a Randomized Controlled Trial of Percutaneous Posterior Tibial Nerve Stimulation for the Treatment of Refractory Fecal Incontinence in Women: The NeurOmodulaTion for Accidental Bowel Leakage Study

Correlation Between Mobile-Application Electronic Bowel Diary and Validated Questionnaires in Women with Fecal Incontinence

INTRODUCTION AND HYPOTHESIS

Despite growing interest in a mobile-app bowel diary to assess fecal incontinence (FI) symptoms, data are limited regarding the correlation between mobile-app diary and questionnaire-based outcomes. The primary aim is to determine whether percentage reduction in FI episodes (FIEs)/week recorded on a mobile-app diary correlates with changes in scores of validated FI-symptom measures from baseline to 12 weeks in women with FI undergoing percutaneous tibial nerve stimulation (PTNS) versus sham.

METHODS

This is a planned secondary analysis of a multicenter randomized trial in which women with FI underwent PTNS or sham. FIEs were collected using a mobile-app diary at baseline and after 12 weekly sessions. FI-symptom-validated measures included St. Mark's, Accidental Bowel Leakage Evaluation, FI Severity Index (FISI), Colorectal Anal Distress Inventory, Colorectal Anal Impact Questionnaire, FI Quality of Life, Patient Global Impression of Improvement (PGI-I), and Patient Global Symptom Control (PGSC) rating. Spearman's correlation coefficient (ρ) was computed between %-reduction in FIEs/week and change in questionnaire scores from baseline to 12 weeks. Significance was set at 0.005 to account for multiple comparisons.

RESULTS

Baseline characteristics of 163 women (109 PTNS, 54 sham) include mean age 63.4±11.6, 81% white, body mass index 29.4±6.6 kg/m2, 4% previous FI surgeries, 6.6±5.5 FIEs/week, and St. Mark's score 17.4±2.6. A significant correlation was demonstrated between %-reduction in FIEs/week and all questionnaires (p<0.005). A moderate-strength correlation (|ρ|>0.4) was observed for St. Mark's (ρ=0.48), FISI (ρ=0.46), PGI-I (ρ=0.51), and PGSC (ρ=-0.43).

CONCLUSIONS

In women with FI randomized to PTNS versus sham, a moderate correlation was noted between FIEs measured via mobile-app diary and FI-symptom-validated questionnaire scores.

Characteristics associated with subjective and objective measures of treatment success in women undergoing percutaneous tibial nerve stimulation vs sham for accidental bowel leakage

INTRODUCTION AND HYPOTHESIS

In randomized trials both percutaneous tibial nerve stimulation (PTNS) and sham result in clinically significant improvements in accidental bowel leakage (ABL). We aimed to identify subgroups who may preferentially benefit from PTNS in women enrolled in a multicenter randomized trial.

METHODS

This planned secondary analysis explored factors associated with success for PTNS vs sham using various definitions: treatment responder using three cutoff points for St. Mark's score (≥3-, ≥4-, and ≥5-point reduction); Patient Global Impression of Improvement (PGI-I) of ≥ much better; and ≥50% reduction in fecal incontinence episodes (FIEs). Backward logistic regression models were generated using elements with significance of p<0.2 for each definition and interaction terms assessed differential effects of PTNS vs sham.

RESULTS

Of 166 women randomized, 160 provided data for at least one success definition. Overall, success rates were 65% (102 out of 158), 57% (90 out of 158), and 46% (73 out of 158) for ≥3-, ≥4-, and ≥5-point St Mark's reduction respectively; 43% (68 out of 157) for PGI-I; and 48% (70 out of 145) for ≥50% FIEs. Of those providing data for all definitions of success, 77% (109 out of 142) met one success criterion, 43% (61 out of 142) two, and 29% (41 out of 142) all three success criteria. No reliable or consistent factors were associated with improved outcomes with PTNS over sham regardless of definition.

CONCLUSIONS

Despite exploring diverse success outcomes, no subgroups of women with ABL differentially responded to PTNS over sham. Success results varied widely across subjective and objective definitions. Further investigation of ABL treatment success definitions that consistently and accurately capture patient symptom burden and improvement are needed.